Air-driven contact filter

Abstract

An air-driven rotary contact filter for biological cleaning of waste water has spiral channels mounted on a perforated rotatable center pipe having its axis of rotation disposed below the surface of the water whereby the filter is partially submerged with inlets to the channels at the central mixing chamber of the rotor below the water surface and some of the outlets at the periphery of the rotor above the water surface, so that when air is blown axially into the center pipe water is displaced on one side of the rotor whereby the channels will rotate due to the greater weight of water on the other side of the rotor.

I claim: 
     
       1. In a rotary contact filter for use in a system for biological cleaning of waste water including a rotor having at least one spiral channel through which air and waste water pass partially submerged in a body of water to be treated and rotatable about a horizontal axis at the central portion of the rotor, the improvement comprising: a mixing chamber in the central portion of said rotor through which the axis of rotation extends;   a central hollow pipe extending through said mixing chamber and having a longitudinal axis coincident with the axis of rotation and being closed at one end thereof;   a source of compressed air connected to the other end of said pipe for feeding air into said pipe;   holes in said pipe for the passage of air from the inside of said pipe to said mixing chamber;   an inner end on said at least one spiral channel communicating with said mixing chamber;   an outer end on said at least one spiral channel passing above the surface of the water during part of the revolution of the rotor;   said rotor having gable plates between which said at least one spiral channel extends; and   openings in said gable plates for the passage of water into said rotor;   said central pipe being disposed below the surface of the water so that said compressed air injected into said pipe passes through said holes into said mixing chamber and into said inlet end of said at least one spiral channel and displaces water in said one spiral channel into a part of said channel on substantially the opposite side of said rotor relative to the axis of rotation from said channel inlet causing said rotor to rotate in the direction opposite to the direction in which the spiral channel extends from the inner end to the outer end thereof.   
     
     
       2. The filter as claimed in claim 1 wherein: said inlets of said spiral channels have substantially the same radius with respect to said axis of rotation; and   said outlets of said spiral channels having substantially the same radius with respect to said axis of rotation.   
     
     
       3. The filter as claimed in claim 1 wherein: said at least one spiral channel comprises a plurality of spiral channels between a pair of said gable plates.   
     
     
       4. The filter as claimed in claim 3 wherein said rotor comprises: a plurality of sets of units of spiral channels, said units being axially spaced between respective pairs of gable plates, each set comprising five units, and every alternate set having the direction of said spiral channels thereof reversed with respect to the adjacent set.   
     
     
       5. The filter as claimed in claim 3 wherein: said spiral channels are formed by a plurality of similar spiral plate members between said pair of gable plates.   
     
     
       6. The filter as claimed in claim 5 wherein: said inlets of said spiral channels have substantially the same radius with respect to said axis of rotation; and   said outlets of said spiral channels have substantially the same radius with respect to said axis of rotation.   
     
     
       7. The filter as claimed in claim 6 wherein said rotor comprises: a plurality of sets of units of spiral channels, said units being axially spaced between respective pairs of gable plates, each set comprising five units, and every alternate set having the direction of said spiral channels thereof reversed with respect to the adjacent set.